This invention is concerned with an osmotic drug (or other beneficial substance) delivery system comprising one or more chambers in series formed by an external shell and chamber-dividing walls of a microporous material and successive overlayers of semipermeable membranes completely covering the outer shell of all but one chamber and substantially covering the outer shell of that one chamber each successive overlayer completely covering all but one more chamber and substantially covering that one more chamber. Osmotic agents, adjuvants, pro-drugs, enzymes, drugs, pesticides, and the like are incorporated in the chambers covered by the semipermeable membranes, and external fluids that diffuse into that chamber form solutions and by osmotic pressure are forced through the microporous chamber-dividing wall to the drug chamber to form a solution thereof and then through the exposed microporous shell to the exterior of the device at a rate controlled by the permeability of the semipermeable overlay and the osmotic pressure gradient across the shell.
By this means there is provided a device for the administration of an active agent at a controlled and continuous rate to achieve a predetermined useful effect in animals including humans.
The advantages of controlled, prolonged release of medicinal agents is well known and several devices for that purpose have been described. Many of these have certain disadvantages which are catalogued in U.S. Pat. No. 3,845,770, which itself describes a controlled release drug delivery system.
The delivery system of U.S. Pat. No. 3,845,770 dispenses a solution of the active agent through a minute orifice in the wall of the device. Such a system tends to administer the active agent at relatively high concentration to a relatively small area of body tissue. In addition the orifice through which the active agent is dispensed can be subject to mechanical plugging. On the other hand, the microporous structure through which the active agent is dispensed in the novel device of the present application distributes the drug from a larger surface, hence larger area of tissue, favoring more rapid and ready absorption without local toxic reaction. In addition there is no propensity to plug as with the prior art device.
Accordingly, it is an object of this invention to:
provide a novel dispensing device for the dispensing of a composition of matter to produce a beneficial effect, which device overcomes the aforesaid disadvantages associated with the prior art devices;
provide a novel dispensing device for dispensing a composition of matter at a controlled rate for a prolonged period of time;
provide a novel and useful dispensing device that is simple in construction, designed with a minimum number of parts, easy to use, and in operation exhibits all the practical and useful benefits obtained by the controlled, continuous long-term administration of various compositions of matter, that is, active agents to animals, avians, humans and into other receptive environments;
provide a novel dispensing device that can administer a complete pharmaceutical dosage regimen for a particular time period, the use of which requires intervention only for initiation and termination of the regimen;
provide an improved dispensing device which will permit high concentration of an active agent to be contained therein, and which high concentration will not exhibit the tendency to be leached from the device nor have its potency decreased by chemical breakdowns;
provide a novel product dispensing device that contains a product which can be used as an osmotically effective solute to exhibit an osmotic pressure gradient against an external fluid;
provide a product dispensing device that contains a product in a form suitable for storage thereby giving the device an improved shelf life;
provide a dispensing device for the administration of locally acting or systematically acting drugs to produce a physiologic or pharmacologic effect and which device can release the drug at a rate that does not vary with time;
provide a device containing drugs in various physiochemical forms such as esters, salts and the like that can be heat sterilized by conventional techniques;
provide a device for dispensing an active agent which device can have a variety of release rates ranging from very low to very high by using polymeric wall forming materials in combination with the active agent or a mixture of an active agent and another osmotically effective compound;
provide a novel and useful erodible or biodegradable device that erodes or degrades after the device has released the active agent;
provide a novel dispensing device with the above-described attributes in a variety of shapes and sizes designed for oral ingestion, implantation, or rectal, vaginal, or ocular insertion.
Other objects, features, and advantages of the invention will be apparent to those skilled in the art from the detailed description of this specification, taken in conjunction with the drawings and the accompanying claims.